The proposed research aims to contribute to an elucidation of the relation between three levels of the process of human speech production: the discrete linguistic representation of an utterance in terms of words and speech segments within words; the acoustic pattern that results from the utterance; and the articulatory gestures that create the link between the linguistic and acoustic representations. Three aspects of this speech chain will be examined: (1) the acoustic and perceptual bases for some of the sounds that occur universally in language, particularly certain features of vowels and of stop, fricative, and nasal consonants; (2) principles that govern the variability in production of speech sounds when the sounds occur in various contexts and are produced with different speech styles, particularly variability due to overlap of articulatory gestures and reduction of vowels in casual speech; and (3) the process by which children in the 3-7 year range acquire the words and sound contrasts in language. The developmental research with children will be based primarily on detailed acoustic analysis and interpretation of the children's utterances as their speech production strategies evolve from whole word units with minimal structure within words to sequences of smaller units that define the contrasts between words. This research will contribute to an understanding of the various stages involved in the production of an utterance, and will help to indicate the components within this process where deviations can occur, and the consequences of these deviations in speech production. It will also contribute to a description of the stages of normal speech development in children and an understanding of the basis for the progression through these stages.